The invention concerns a circuit arrangement for amplifying a weak direct voltage signal using a direct voltage amplifier that can be periodically switched through a switching member with a periodical short-circuiter on its input terminals from the direct voltage signal to a reference signal and provides adjustment with a measurement value processor connected downstream of the direct voltage amplifier when a reference signal is applied.
A circuit means of this kind is known from the journal Review of Scientific Instruments, 59 (1988), July, No. 7, pp. 1241-1243. In this device, a direct voltage amplifier can be insulated from the voltage to be measured by a short-circuiter on the input side and connected to ground. If the direct voltage amplifier is short-circuited on its input side, its output voltage is dependent only on the offset; an output voltage of the direct voltage amplifier produced in this switching state is stored in an additional circuit unit. If, in a subsequent measuring period, the direct voltage amplifier is again at the direct voltage to be measured, the stored output voltage corresponding to the offset voltage is then subtracted from the output voltage thus obtained.